Language minority students' writing is often measured solely in terms of its distance from native speaker norms, yet doing so may ignore the process through which these texts are realized and the role that the first language plays in their creation. This study analyzes oral interactions among adolescent second language writers during an extended writing activity to address the following questions: (1) How do students use their first language(s) to broker L2 interactions with a monolingual teacher during L2 writing tasks?; (2) How do students use their first language(s) in student-student interactions to demonstrate expertise during L2 writing tasks?; and (3) How do students use their first language(s) in student-student interactions to seek expertise during L2 writing tasks? Analysis of student-teacher and student-student interactions reveals that L1 use offers strategic opportunities for student-teacher conversation and blurs traditional boundaries between "expert" and "novice" writers. Bilingual students at all levels of English language proficiency utilize the L1 to assert expertise in rhetorical, academic, linguistic, or procedural elements of the task, and students move fluidly between expert and novice roles. There are limits to students' expertise, however, as well as the pedagogical circumstances under which the L1 can be most productively used. These findings offer insight into the writing process as it is influenced by bilingual language proficiencies and classroom interaction. (Contains 1 figure, 1 table, and 6 transcripts.)